1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device, a driving method thereof, a manufacturing method thereof, and the like.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition (a composition of matter). Therefore, more specifically, as the technical field of one embodiment of the present invention disclosed in this specification, a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a storage device, a driving method of them, or a manufacturing method of them can be given.
2. Description of the Related Art
As for pixels of active matrix display devices using light-emitting elements, a variety of circuit configurations are proposed by every manufacturer. In general, a pixel is provided with at least a light-emitting element, a transistor which controls input of a video signal to the pixel (switching transistor), and a transistor which controls a current supplied to a light-emitting element (driving transistor). Supplying a source-drain current (hereinafter, referred to as a drain current in some cases) flowing in the driving transistor to the light-emitting element makes the light-emitting element emit light at a luminance corresponding to the value of the drain current. The drain current value of the driving transistor is controlled by the potential of a video signal.
Therefore, when there is variation in the threshold voltage of the driving transistor between a plurality of pixels included in a screen of a display device, even when video signals with the same potential are supplied to these pixels, variation in the luminance of the light-emitting element is caused. The variation in the threshold voltage of the driving transistor between a plurality of pixels is one cause of a reduction in the display quality of the display device. Meanwhile, an increase in the number of pixels in an active matrix display device is advanced to increase the resolution, and as many as hundreds of thousands to tens of millions of pixels are provided in one display device. For example, in the case of a resolution of full-HD, the number of pixels is 1366×768×3 (RGB)=1,049,088; and in the case of 8k4k (Super Hi-Vision), it is 7,680×4,320×3 (RGB)=33,177,600. It is highly difficult to make the threshold voltages of driving transistors in such a large number of pixels completely equal to each other. Thus, to suppress an influence of the variation in the threshold voltage, a pixel which is capable of correcting the threshold voltage of a driving transistor is proposed (see Patent Documents 1 and 2).